Refrigeration apparatus



July 14, 1953 G. s. M CLOY REFRIGERATION APPARATUS 2 Sheets-Sheet 1Filed March 1, 1950 INVENTOR GRAHAM S. MG LOY ATTORNEY July 14, 1953 G.s. MCCLOY 2,645,094

REFRIGERATION APPARATUS Filed March 1, 1950 2 Sheets-Sheet 2 F IG .3.WITNESSES: INVENTOR I GRAHAM s. MCCLOY I ATTORNEY Patented July 14, 1953UNITED STATES PATENT OFFICE REFRIGERATION APPARATUS Graham S. McCloy,Springfield, Mass., assignor to Westinghouse Electric Corporation, EastPittsburgh, Pa., a corporation of Pennsylvania Application March 1,1950, Serial No. 146,960

7 Claims.

This invention relates to refrigerating apparatus and more especially totemperature regulating devices for refrigerators equipped with rapiddefrosting means.

The temperature regulating device of refrigerators preferably comprisesa temperature-responsive element located in the refrigerated chamber andconnected to the cooling unit by a metallic strip of limitedheat-conducting capacity. This construction provides that thetemperatureresponsive element is responsive to the temperature of theair in the chamber as well as to the temperature of the cooling unit.The latter is necessary to prevent over-running of therefrigerant-supplying apparatus. By over-running is meant the cooling ofthe cooling'unit to a very low temperature merely because of the timelag between the cooling of the evaporator and the resulting cooling ofthe air in the cabinet.

In a refrigerator in which the cooling unit is rapidly defrosted such asby conducting warm refrigerant liquid through its refrigeratingpassages, a temperature-sensitive element so mounted defrosts moreslowly than the evaporator and may not defrost completely during thedefrosting operation. This is caused by the fact that the warmrefrigerant liquid is only in limited heattransfer relationship with thetemperature-sensitive element. If the temperature-sensitive element isnot completely defrosted at the end of an automatically controlleddefrosting operation, the frost thereon will be still thicker at the endof the next automatic defrosting operation and the thickness of thisfrost will gradually increase until it interferes with the properfunctioning of the refrigerator.

Accordingly, it is an object of this invention to provide thermostaticmeans for controlling the temperature of a refrigerator which means isresponsive to the temperature of the air in the refrigerator and whichmeans is positively defrosted during the defrosting of the cooling unit.

It is a further object of the invention to provide effective means forcontrolling the temperature of a refrigerator.

These and other objects are effected by my invention as will be apparentfrom the following description and claims taken in connection with theaccompanying drawings, forming a part of this application, in which:

Fig. l is a somewhat schematic drawing of a vertical sectional view of arefrigerator embodying the thermostatic control of this invention;

Fig. 2 is a vertical sectional view'of the refrigerant liquid storagechamber of the refrigerator;

Fig. 3 is a partial vertical sectional view similar to the Fig. 1 butshowing a modification of the invention; and

Fig. 4 is similar to Fig. 3'but shows another modification of theinvention.

Referring to the drawings for a description of the invention, thereference numeral l0 designates a refrigerator cabinet having a foodstorage chamber l2 in the upper portion thereof and a machinecompartment l4 below the food storage chamber. The food storagechamberI2 is surrounded by thermal insulation l6. A sealed casing IS in themachine compartment [4 contains a compressor and an electric motor 22for driving the same. An inlet port 24 of the compressor Z0 communicateswith the interior of the sealed casing l8. A pressure conduit-26 leadsthe refrigerant vapor compressed by the compressor 20 to an air-cooledcondenser 28. A capillary tube 30 conducts the refrigerant liquid formedin the condenser 28 to a larger tube 32 located in the thermalinsulation I6 of the cabinet Ill. The refrigerant liquid vaporizes inpart in the tube 32 and then flows into an accumulator 34 forming a partof the rapid defrosting device of the refrigerator.

A second tube 36 communicates at one end 33 with a lower portion of theaccumulator 34, then rises upwardly above the accumulator 34 and returnsdownwardly through the accumulator 34 and at its other end 40 connectswith an evaporator 42. A small opening 44 is provided in the tube andcommunicates with an upper portion of the accumulator 34. During therefrigerating operation of the apparatus, the accumulator 34 is filledwith refrigerant liquid to the level of the hole 44, and the refrigerantliquid and vapor flows through this hole 44 and through the lowerportion of the tube 36 into the evaporator 42.

A suction tube 46 conducts the vaporized refrigerant from the evaporator42 downwardly to the casing l8. The suction tube 46 has a portion 48 inheat-transfer relationship with a portion 50 of the capillary tube 30and a lower portion 52 in heat-transfer relationship with the pressureconduit '26.

The thermostatic control of this invention comprises a blind metal tube55 which communicates with the accumulator 34 and extends upwardlytherefrom.

The electric motor 22 receives its power from the lines 58 through theleads 60. A thermostatic switch 62 is located in one of the leads and iscontrolled by a temperature-sensitive bulb 64 located at the upperend ofthe blind tube '56.

The bulb 64 contains a volatile fluid, the vapor pressure of which istransmitted to the thermostat 62 through a tube 66. When the temperatureof the bulb 64 and consequently the vapor pressure of the liquid thereinexceeds a certain limit, the switch of the thermostat 62 is closed andwhen the temperature of the bulb 64 drops to a lower limit the switch inthe thermostat 62 is opened so that the refrigerating apparatus isactuated to hold the temperature of the bulb 64 between two fixedtemperature limits. Both of these limits are far below the freezingpoint of water so that the evaporator, the tube, and the bulb 64accumulate a coating of frost.

A heater 68 is located adjacent the tube 32 to heat the same and iscontrolled by a switch located in a controller 10. Leads 12 connect theheater 68 and the switch of the controller in series with leads 60. Thecontroller 10 is of the type described in the patent application, SerialNo. 143,788, filed February 11, 1950, by the inventor of this invention,now Patent No. 2,595,967, granted May 6, 1952, and comprises a countingdevice which is actuated through a plunger 14 to close the switch of thecontroller 10 when the door 15 has been opened and closed a certainnumber of times, such as sixty times. The switch of the controller 10 isagain opened by a thermostat comprising a tube 16 and atemperatureresponsive bulb 18 located on the evaporator 42. When theevaporator 42 attains a temperature of above freezing the vapor pressureof a volatile liquid in the bulb I8 acts through the tube 16 to open theswitch in the controller 10.

The defrosting action of this refrigerator is described and claimed inPatent No. 2,459,173, issued January 18, 1949, to the inventor of thisinvention and functions as follows: when the door of the refrigeratorhas been opened and closed the required number of times, the switch inthe controller 70 is closed and when the switch in the thermostat 62also closes, the heater 68 will be energized. When the heater 68 isenergized, some of the refrigerant liquid in the tube 32 is vaporized sothat an abnormal quantity of the refrigerant vapor enters theaccumulator 34. This vapor is too large in volume to flow through theopening 44 in the tube 36 at the prevailing pressure. Consequently thepressure in the accumulator 34 rises until the refrigerant liquid isforced from the accumulator 34 through the end 38 of the tube 36. Thisrefrigerant liquid is warmed by the warm vapor generated in the tube 32by the heater 68.

The added refrigerant liquid transferred to the evaporator 42 from theaccumulator 34 floods the evaporator 42 and runs downwardly through thesuction tube 46 and through the portion 52 thereof which is inheat-exchange relationship with the pressure conduit 26. The liquidrefrigerant is vaporized completely in the portion 52 of the suctionconduit 46 by the heated vapor in the pressure conduit 25. This raisesthe suction pressure in the apparatus so that no further vaporizationoccurs in the evaporator 42 and so that the latter is defrosted by thewarm refrigerant issuing from the accumulator 34.

Operation suction pressure as the evaporator 42 and cools therefrigerant liquid flowing therethrough by vaporizing a portion of thisliquid.

During the refrigeration of the food storage chamber 12, the upper endof the blind tube 56 and the temperature-sensitive bulb 64 is warmerthan the accumulator 34 because the tube 56 and the bulb 64 extend intothe warmer air of the food storage chamber l2, The major portion of theheat-transfer from the bulb 64 to the accumulator 34 takes place only byconduction along the metal wall of the tube 56, since the vapor in thetube 56 cannot condense and hence does not circulate in the tube 56.

During the defrosting operation, the accumulator 34 is warmed by thewarm refrigerant vapor entering it from that portion of the tube 56which is in contact with the heater 68. This warm vapor entering theaccumulator 34 also enters the tube 56, and since its temperature ishigher than that of the tube 56 it will condense and the resultingcondensate run down into the accumulator 34. The tube 56 will thus bewarmed at substantially the same rate as the accumulator 34. Theaccumulator 34, furthermore, is warmer than the main evaporator 42because it receives the warm refrigerant directly from the tube 32 andis the first portion of the evaporator system of the refrigerator whichis defrosted. The tube 56 and the bulb 64, therefore, will be thoroughlydefrosted.

Modifications Fig. 3 shows a modification of the invention in which ablind tube 80, similar to the blind tube 56, is secured to andcommunicates with the header 82 of the evaporator 42. In this figure,the elements which are similar to the elements of the previouslydescribed modification are provided with the same reference numerals,respectively. The defrosting action of the tube 85 is similar to thattube 56 but is somewhat slower because the tube is farther removed fromthe heater 68. The blind tube 80 can also communicate with a portion ofthe evaporator 42 which contains refrigerant liquid since this liquidwould not enter the blind tube 80 because of the higher temperature ofthe latter.

Fig. 4 shows a further modification of the invention. In thismodification a tube 84, closed at both ends, is employed. The tube 84contains a small quantity of a volatile liquid and the vapor of thisliquid is quiescent during the refrigeration operation of the apparatusbut becomes active to warm the bulb 64 when the evaporator 42 tends tobecome warmer than the bulb 64 in the same manner as previouslydescribed.

It will be apparent from the above that this invention provides amounting for the thermostatic control of a refrigerator which mountingprovides a response to the temperature of the air in the refrigeratedcabinet and also insures positive defrosting of the control when thecooling unit of the refrigerator is defrosted.

While I have shown the invention in several forms, it will be obvious tothose skilled in the art that it is not so limited, but is susceptibleof various changes and modifications without departing from the spiritthereof.

What I claim is:

1. In a refrigerator comprising a chamber and refrigerating apparatus,said apparatus comprising a low pressure side including a cooling unitfor cooling said chamber and means for periodically defrosting saidcooling unit, said means ineluding an accumulator of refrigerant liquid,said apparatus also including a high pressure side .1 or condensing therefrigerant vapor produced in said low pressure side, a pump fortransferring refrigerant vapor from the low pressure side to the highpressure side, a temperature-responsive element for controlling saidpump, said element being respbnsive to the temperature of the air insaid chamber, and a tubular heat-conducting member having upper andlower ends, the upper end of said member being closed and arranged inheat-transfer relationship with said element and the lower end thereofcommunicating with said accumulator, the construction and arrangement ofsaid member being such that its conductivity is relatively low when saidaccumulator is colder than said element and relatively high whenaccumulator is warmer than said element.

2. In a refrigerator comprising a chamber, evaporator for cooling saidchamber, said evaporator having a passage, operating means for supplyingrefrigerant liquid to said passage and for withdrawing refrigerant vaportherefrom, a tu bular member formed of heat-conducting material andclosed at one end, said member having an upper and a lower portion, thelower portion of 7 said member communicating with said passage and lyingin heat-conducting relationship with said evaporator, the upper portionof said member being exposed to the air in said chamber, a thermostatincluding a temperature-responsive element, said element lying inheat-transfer relationship with the upper portion of said member, saidthermostat controlling said operating means to activate the same whenthe temperature of said temperature-responsive element rises to above acertain value and to inactivate said operating means when saidtemperature drops to acertain value below 32 F. and heating means forwarming said evaporator to above 32 F. to melt frost thereon.

3. The refrigerator defined in claim 2 wherein said heating meanscomprises means for so altering the action of said operating means thatit supplies to and withdraws refrigerant liquid at a temperature ofabove 32 F. from said passage.

4. In a refrigerator comprising a chamber, an evaporator for coolingsaid chamber, operating means for supplying refrigerant liquid to saidevaporator and for withdrawing refrigerant vapor therefrom, a closedtubular member formed of heat-conducting material, said member having anupper and a lower portion, the lower portion of said member being inheat-conducting relationship with said evaporator, the upper portion ofsaid member being exposed to the air in said chamber, a volatile fluidin said member, a thermostat including a temperature-responsive elementlying in heat-transfer relationship with the upper portion of saidmember, said thermostat controlling said operating means to activate thesame when the temperature of said temperatureresponsive element rises toabove a certain value and to inactivate said operating means when saidtemperature drops to a certain value below 32 F. and heating means forwarming said evaporator to above 32 F. to melt frost thereon.

5. The refrigerator defined in claim 4 wherein said heating meanscomprises means for so altering the action of said operating means thatit supplies to and withdraws refrigerant liquid at a temperature ofabove 32 F. from said evaporator.

6. In a refrigerator comprising a chamber, a refrigerating system forcooling media in said chamber, said system comprising a low pressureside for vaporizing a volatile fluid, a high pressure side forcondensing the vapor produced in said low pressure side and a pump fortransferring vapor from said low pressure side to said high pressureside, a temperature-responsive element for controlling said pump, aheat-conducting member thermally connecting said ele ment and a portionof said low pressure side within said chamber, said heat-conductingmember comprising a tubular member sealed from the air ambient saidsystem and containing a volatile fluid, said member having upper andlower portions, the upper portion of said member being in heat-exchangerelationship with said element and the lower portion of said memberbeing in heat-exchange relationship with said portion of the lowpressure side, and means for applying heat to the low pressure side ofsaid system to effect defrosting of said system.

7. In a, refrigerator comprising a chamber, a refrigerating system forcooling media in said chamber, said system comprising a low pressureside for vaporizing a volatile fluid, a high pressure side forcondensing the vapor produced in said low pressure side and a pump fortransferring vapor from said low pressure side to said high pressureside, a temperature-responsive element for controlling said pump, saidtemperatureresponsive element being responsive, at least in part, to thetemperature of the air in said chamber, a heat-conducting memberconnecting said element and a portion of said low pressure side whichcontains refrigerant liquid, said heat-conducting member comprising ablind tube connected to and in communication with a portion of said lowpressure side and extending to a. region above the refrigerant liquidlevel in said portion, and means for periodically warming said lowpressure side to above 32 F. to melt frost thereon.

GRAHAM S. MCCLOY.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,913,433 Dable June 13, 1933 2,036,565 Brouse Apr. 7, 19362,042,568 Tuska June 2, 1936 2,064,396 Volpin Dec. 15, 1936 2,169,284Ploeger Aug. 15, 1939 2,192,848 Buchanan Mar. 5, 1940 2,208,267 RidgeJuly 16, 1940 2,324,309 McCloy July 13, 1943 2,366,635 McCloy Jan. 2,1945 2,459,083 McCloy Jan. 11, 1949 2,459,173 McCloy Jan. 18, 1949

